The present invention relates to organopolysiloxane-polyoxyalkylene emulsifiers for polar in nonpolar liquid emulsions, e.g., water in oil. While such emulsifiers have a wide variety of applications, it has been found that they do not reliably stabilize emulsions which are used in high temperature applications or which are subject to extreme temperature variations in use or storage.
For example, it has been suggested that organopolysiloxane-polyoxyalkylene emulsifiers be used to stabilize heavy brine in oil emulsions used in various oil field applications. However, such emulsions are subject to temperatures of 250 to 550 degrees F. and to substantial pressures, e.g., 30,000 psi and higher. It has been found that existing organopolysiloxane-polyoxyalkylene emulsifiers do stabilize such emulsions sometimes, but not reliably on a repeat basis.
Similarly, some emulsion products must withstand freeze thaw stability variations of from as much as -20 degrees C. to as much as 60 degrees C. One test specified by some manufacturers requires that such emulsions remain stable after cycling from -12 degrees C. to room temperature every day for 28 days. As above, organopolysiloxane-polyoxyalkylene emulsifiers are sometimes operable in such environments, but not reliably so.
Too often, emulsions stabilized by organopolysiloxane-polyoxyalkylene emulsifiers break down when subjected to conditions such as those described above. It is believed that no suitable explanation for the spotty performance of such emulsifiers has heretofore been offered. Nor has any solution to the problem been effected.